docs: def pack(self, topic_dims, t):
          """ Packs selected logs into a numpy array
              :param list topic_dims: list of (topic, dims) tuples, where topic is a string and dims a list dimensions to be packed for that topic
              :param int t: time indexes to be packed
          """
  
          data = []
          for topic, dims in topic_dims:
              for d in dims:
                  data.append(self.logs[topic][t, d])
          return array(data).T